Advertise 1.8.9

Author: Stephane Landelle

README.md

@@ -10,7 +10,7 @@ Async Http Client library purpose is to allow Java applications to easily execut
 <dependency>
  <groupId>com.ning</groupId>
  <artifactId>async-http-client</artifactId>
- <version>1.8.8</version>
+ <version>1.8.9</version>
 </dependency>
 ```